Lubricating oil composition

Abstract

A crankcase lubricating oil composition comprising (A) an oil of lubricating viscosity in a major amount; and (B) an additive component in a minor amount comprising one or more oil-soluble sterically unhindered meta-hydrocarbyl substituted phenols.

What is claimed is: 
     
       1. A crankcase lubricating oil composition comprising or made by admixing
 (A) an oil of lubricating viscosity in a major amount; and 
 (B) an additive component in a minor amount comprising, one or more oil-soluble sterically unhindered meta linear pentadecenyl-substituted phenols, which are unfunctionalised or functionalised, the composition comprising less than 0.8 mass % of an aminic anti-oxidant and/or less than 0.5 mass % of a hindered phenolic anti-oxidant, provided that when (B) is unfunctionalised, the composition does not contain a sulphurised mixture of alkenes. 
 
     
     
       2. A composition as claimed in  claim 1  where the meta substituent is an 8-pentadecenyl or a pentadecyl group. 
     
     
       3. A composition as claimed in  claim 1  where (B) comprises distilled cashew nut shell liquid (or cardanol) or hydrogenated distilled cashew nut shell liquid. 
     
     
       4. A composition as claimed in  claim 2  where (B) comprises distilled cashew nut shell liquid (or cardanol) or hydrogenated distilled cashew nut shell liquid. 
     
     
       5. A composition as claimed in  claim 1  where (B) is a mixture of oil-soluble phenolic compounds comprising 50 or more mass % of one or more of the sterically unhindered meta substituted phenols. 
     
     
       6. A composition as claimed in  claim 5  where (B) is a mixture of oil-soluble phenolic compounds comprising 70 or more mass % of one or more of the sterically unhindered meta substituted phenols. 
     
     
       7. A composition as claimed in  claim 6  where (B) is a mixture of oil-soluble phenolic compounds comprising 90 or more mass % of one or more of the sterically unhindered meta substituted phenols. 
     
     
       8. A composition as claimed in  claim 1  where the phenol has the formula: 
       
         
           
           
               
               
           
         
         where R is a linear C 15 H 25-31  hydrocarbyl group attached to the aromatic nucleus at its C1 position and X is a hydrogen atom or a hydroxy group. 
       
     
     
       9. A composition as claimed in  claim 8  further including one or more other additive components, different from (B). 
     
     
       10. A composition as claimed in  claim 9  where the other additives, different from (B), are selected from one or more ashless dispersants, metal detergents, corrosion inhibitors, antioxidants, pour point depressants, antiwear agents, friction modifiers, demulsifiers, antifoam and viscosity modifiers. 
     
     
       11. A method of enabling a passenger car crankcase lubricating oil composition to achieve improved anti-oxidancy performance, which method comprises providing the composition with minor amounts of one or more additives (B) as defined in  claim 1 . 
     
     
       12. A method of lubricating surfaces of an internal combustion engine during its operation comprising:
 (i) providing, in a minor amount, one or more additives (B) as defined in  claim 1  in a major amount of an oil of lubricating viscosity to make a lubricant, to improve the anti-oxidancy properties of the lubricant; 
 (ii) providing the lubricant to the crankcase of the internal combustion engine; 
 (iii) providing a hydrocarbon fuel in the combustion chamber of the engine; and 
 (iv) combusting the fuel in the combustion chamber.